轻型井点降水发生透点的处理

介绍了判断轻型井点降水是否发生透点现象的方法，从施工现场地质条件、降水设备及井点管长度误差三方面，就发生透点的原因进行了分析，提出了相应的排除和防治措施。     

任意排列的承压-潜水完整型干扰井群计算理论及应用

井点降水是深基坑和地下构筑物施工中常用的降低地下水位的方法。稳定流理论作为非稳定流理论的特例，在干扰井群计算中应用较广泛。在具体的水文地质条件下，干扰井群经常被概化为一个水文地质模型，进而构成相应数学模型。基于稳定流理论，建立了地下水动力学模型，引入势函数和势的迭加原理，考虑所有任意排列的抽水井对所求点的水位降深影响，以及不同含水层的不同渗透系数，推导了任意排列的承压．潜水完整型干扰井群的理论计算公式。结合具体工程实例，应用所推导的计算公式，得出的降水计算结果，与实际降水结果吻合良好。     

污染物运移过程的一维数值分析

考虑填埋场中固体废弃物的生物降解效应和含水层中土颗料对污染物的吸附性,在有限深度条件下基于对流、弥散和地球化学反应等污染物运移机理,提出了填埋场污染物运移过程数值模拟的一维计算模型。进而采用半解析方法进行数值求解,通过变动参数比较分析确定了控制填埋场污染物运移过程的主要参数。具体数值计算表明:污染物在含水层中运移浓度将于某一特定时间达到峰值,随后逐渐降低。粘土垫的厚度及其渗透性、压缩粘土垫层与含水层的吸附能力是填埋场污染物运移的重要近控制参数。     

Relationship between the concentration of denitrifiers and Pseudomonas spp. in soils: Implications for BTX bioremediation

Aquifer microcosms were used to investigate the effect of stimulating denitrification on microbial population shifts and BTX degradation potential. Selective pressure for facultative denitrifiers was applied to a treatment set by feeding acetate and nitrate, and cycling electron acceptor conditions twice between aerobic and denitrifying stages. A second (control) set degraded the same amount of acetate under aerobic conditions. The resulting concentrations of total heterotrophs were not significantly different between the two sets. Nevertheless, the concentrations of denitrifiers, Pseudomonas spp., and BTX degraders were significantly higher in the cycled microcosms than in the aerobic controls. The predominant isolates from the cycled microcosms were fluorescent Pseudomonas species that are known to degrade BTX. Following the complete removal of acetate, cycled microcosms also showed higher aerobic BTX degradation activity. These results suggest that nitrate addition to oxygen-limited aquifers might enhance BTX bioremediation not only by supplementing the electron acceptor pool as is widely accepted, but also by fostering favorable changes in the composition of the microbial consortium. Specifically, denitrifying conditions could have the ancillary benefit of fortuitously selecting for Pseudomonas spp. that can degrade BTX. This syllogism is supported by a survey of international soils (from France, Denmark, Brazil and Iowa, USA), which showed a correlation between the concentration of denitrifers and Pseudomonas spp.     

上海地铁2#线淤泥质地层地铁隧道浅埋暗挖施工技术方案研究

结合上海地铁2#线西延伸工程威宁路站3#出入口通道工程,介绍了在上海含水淤泥质地层条件下,采用管幕超前预支护、掌子面深孔注浆加固、短开挖、强支护等综合浅埋暗挖施工技术。并应用大型有限元软件——ANSYS,采用有限元数值方法对其施工效应进行了计算分析。分析结果表明,施工过程中洞室结构稳定,浅埋暗挖管幕预支护施工方法可行,并可实现洞内施工安全和施工地面沉降的控制要求,解决了明挖施工对城市交通的干扰,所得结果可为后续类似工程提供一定的理论参考。     

井点降水引起的复合地基沉降问题讨论

在实际工程中，由深基坑开挖而引起的邻近土体水平位移和竖向位移，通常与基坑降水引起的变形耦合在一起，使土体变形更加复杂。按经典稳定流理论来预测降水邻域内复合地基沉降值与实测结果有较明显的差异。实践证明，利用半理论、半统计的方法预测复合地基沉降是一条可行的技术路线。     

考虑渗流与应力耦合的基坑降水数值模型研究

针对目前应用广泛的解析计算方法,本文分析了砂土地基基坑工程井点降水的特点,基于有限元理论,考虑降水过程中渗流场与应力场的耦合作用,建立了考虑应力与渗流耦合的基坑降水的数值模型,并应用该模型分析地下水水位随时间的下降过程。工程实例分析表明,该模型比较符合实际情况,具有较强的适用性。     

多支护形式在复杂环境深基坑中的应用

介绍了某深基坑的施工,根据场地周边不同条件分别采用不同支护方案的设计施工要点。支护桩、水泥土墙、高压喷射注浆止水帷幕、深层搅拌桩止水帷幕、挂网喷护和井点降水等多种支护手段的综合利用,降低了成本,缩短了工期。     

海口市污水处理厂污泥消化的运行分析

白沙门污水处理厂(30×104m3/d)是海口市利用德国政府软贷款兴建的第一座城市污水处理厂,处理工艺为高负荷生物处理加深海排放。2005年以前,该厂污泥仅经重力浓缩后直接离心脱水。在消化池投入运行后,污泥利用厌氧消化进行稳定处理及离心脱水,产生的沼气用来发电,其废热用于加热消化池污泥。从消化对污泥脱水、污泥量及其经济效益和环境影响等方面进行对比分析,阐明消化作为稳定工艺的必要性。在运行中应加强对沼气脱硫塔的维护,避免由于磷酸铵镁(MAP)的形成而堵塞污泥管道,同时还应积累对沼气发电机组的操作及其维护的经验。     

Drainage from Roads and Airfields to Soakaways: Groundwater Pollutant or Valuable Recharge?

The construction of a road, runway or other paved surface on the outcrop of an aquifer introduces an impermeable area into an otherwise permeable environment. Surface water must be drained from these areas, and the most convenient and inexpensive way of disposing of this water is usually to lead it into soakaways in the unsaturated zone of the aquifer. This approach is acceptable in that it can provide valuable recharge to aquifers in times of low rainfall. However, it carries the risk that pollutants from the surface can also be carried into the aquifer. These pollutants can be generated from (a) normal abrasion, (b) maintenance operations such as de-icing and defoliation, and (c) accidental spillages. Although there is evidence that such drainage can carry a pollutant load, and that drainage entering soakaways can reach a public- supply well, there does not seems to be any evidence available at present of any public supply in the UK being seriously affected by such drainage.